Implantable facet fusion devices

ABSTRACT

Implantable devices for the treatment of degenerative facet joint disease, and more specifically to implantable devices for the immobilization or fusion of degenerated facet joints, particularly of the cervical spine are provided. The devices may be easily inserted into the facet joint, promoting fusion and initiating a natural healing response. Also provided are methods of treating degeneration of a facet joint using these implantable devices.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.13/770,713 filed Feb. 19, 2013 (now U.S. Pat. No. 9,717,603), whichclaims benefit of U.S Provisional No. 61/600,185 filed Feb. 17, 2012 andentitled “Implantable Facet Fusion Devices,” the entire disclosures ofwhich are hereby incorporated by reference.

FIELD

The present disclosure relates to implantable devices for the treatmentof degenerative facet joint disease, and more specifically toimplantable devices for the immobilization or fusion of degeneratedfacet joints, particularly of the cervical spine.

BACKGROUND

Facet joints are the hinge-like joints that connect vertebrae together.They are located at the back of the spine (posterior), and workalongside the vertebral discs to form a functional working unit of thespine. These joints help support the weight of the vertebra, and controlmovement between individual vertebrae of the spine, such as flexion,extension and twisting motions. In addition, the facet joints aresynovial joints, which means each joint is surrounded by a capsule ofconnective tissue and produces a fluid to nourish and lubricate thejoint. Cartilage coats the joint surfaces and allows the joints to moveor glide smoothly against each other.

As with other bone joints, facet joints are almost constantly in motionwith the spine, and are therefore susceptible to degeneration such asfrom osteoarthritis. Degenerative facet joint disease is a type ofosteoarthritis that can cause the break down of the cartilage coveringthe facet joint surfaces, the result of which is jointinflammation-degradation in the spine that can lead to bone spurs orenlargement of the joints. The disease itself may be due to simple wearand tear associated with aging, or due to severe obesity. Thepredominant symptom is back pain on motion, particularly at the joint orjoints where the condition is present. Other symptoms that can occur areswelling, reduced range of motion, and muscle weakness.

There is no known cure for spinal osteoarthritis. Current treatmentsfocus on reducing pain and slowing down the disease progression. Thesetreatments vary depending on the degree of joint damage but can includelifestyle changes, over-the-counter or prescription painkillers andphysical therapy. Another common treatment is injection into theaffected facets, such as with an anesthetic numbing agent forshorter-term results or a corticosteroid for longer-term results.

Like other bone joints that have degenerated, more invasive treatmentssuch as surgery may be used in certain cases. It can be useful toimmobilize the affected spinal motion segment in order to stabilize thespine as well as reduce the pain associated with motion of the damagedjoint. This can be particularly applicable in the cervical spine, wherechronic neck pain is prevalent in interventional pain managementpractices. Accordingly, it is desirable to provide implantable devicesthat are well suited for immobilization of diseased facet joints, and inparticular cervical facet joints. The implantable devices should be easyto implant and provide structural integrity to the area to be treated.Even more desirable are implantable devices that also promote fusion ofthe damaged cervical facet joint in order to provide a longer-termsolution to chronic neck pain.

SUMMARY

The present disclosure provides implantable devices for the treatment ofdegenerative facet joint disease, and more specifically to implantabledevices for the immobilization or fusion of degenerated facet joints,particularly of the cervical spine.

In one embodiment, an implantable device for cervical facet fusion isprovided. The device comprises an elongate main body extending between afirst, leading end and a second, trailing end, the first, leading endterminating into a tapered nose having a sharp cutting edge, and aseries of cutting fins arranged along a helical spiral down the lengthof the elongate main body. The cutting fins roughen the bone tissueduring insertion, thereby initiating a healing response that promotesfusion.

In another embodiment, an implantable device for cervical facet fusionis provided. The device comprises an elongate main body extendingbetween a first, leading end and a second, trailing end, the first,leading end terminating into a tapered nose having a sharp cutting edge,and a plurality of openings along the length of the elongate main body.The openings facilitate bony ingrowth after implantation.

In still another embodiment, an implantable device for cervical facetfusion is provided. The device comprises an elongate main body extendingbetween a first, leading end and a second, trailing end, the first,leading end terminating into a tapered nose having a sharp cutting edge,and a series of cutting fins arranged along a helical spiral down thelength of the elongate main body. A plurality of grating holes are alsoprovided along the elongate main body. The cutting fins and gratingholes roughen the bone tissue during insertion, thereby initiating ahealing response that promotes fusion.

In yet another embodiment, a method of treating degeneration of a facetjoint is provided. The method comprises providing an implantable devicecomprising an elongate main body extending between a first, leading endand a second, trailing end, the first, leading end terminating into atapered nose having a sharp cutting edge, and a plurality of cuttingfins arranged along a helical spiral down the length of the elongatemain body; drilling a pilot hole into a targeted site of the facet jointto be treated; inserting the implantable device into the pilot hole; anddelivering the implantable device into the targeted site. The facetjoint may be a cervical facet joint.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory onlyand are not restrictive of the disclosure. Additional features of thedisclosure will be set forth in part in the description which follows ormay be learned by practice of the disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate several embodiments of thedisclosure and together with the description, serve to explain theprinciples of the disclosure.

FIG. 1A is a planar side view of an exemplary embodiment of animplantable device of the present disclosure.

FIG. 1B is a perspective view of the implantable device of FIG. 1A.

FIG. 1C is another perspective view of the implantable device of FIG.1A.

FIG. 2A is a planar side view of another exemplary embodiment of animplantable device of the present disclosure.

FIG. 2B is a perspective view of the implantable device of FIG. 2A.

FIG. 3A is a planar side view of yet another exemplary embodiment of animplantable device of the present disclosure.

FIG. 3B is a perspective view of the implantable device of FIG. 3A.

FIG. 3C is another perspective view of the implantable device of FIG.3A.

FIG. 4 is a perspective view of still another exemplary embodiment of animplantable device of the present disclosure.

FIG. 5 is a perspective view of even still another exemplary embodimentof an implantable device of the present disclosure.

FIGS. 6A-6I illustrate an exemplary method of inserting the implantabledevices into a facet joint of the cervical spine.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory onlyand are not restrictive of the disclosure. Additional features of thedisclosure will be set forth in part in the description which follows ormay be learned by practice of the disclosure.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The present disclosure provides implantable devices for the treatment ofdegenerative facet joint disease, and more specifically to implantabledevices for the immobilization or fusion of degenerated facet joints,particularly of the cervical spine. Also provided are methods ofimplanting and using these devices.

Turning now to the drawings, FIG. 1A shows an exemplary embodiment of animplantable device 100 of the present disclosure. Implantable device 100may comprise an elongate main body 110 terminating at a first, leadingend 112 and at a second, trailing end 114 at an opposite end. The first,leading end 112 may taper into a rounded nose 116. However, the nose 116does not need to be limited to such and could be bullet shaped, conical,or any other shape as desired for ease of insertion.

The main body 110 may be cannulated, and include a central channel 118as shown in FIG. 1B. The central channel 118 allows the device 100 to beused with a guidewire during insertion. The device 100 may be insertedthrough a pre-drilled pilot hole on a diseased facet using a guidewire,for example. A tool-engaging opening 122 at the second, trailing end114, as shown in FIG. 1C, can be provided to allow the device 100 toquickly attach and detach from a driver tool for insertion into thepre-drilled hole and into the facet. The opening 122 could be, forexample, a hex opening as shown, although other configurations arecontemplated. For instance, the opening 122 could be threaded to allow athreaded connection with the insertion tool. Other types of connectionsknown to those skilled in the art may be interchangeable with the oneshown and described herein.

As further shown in FIGS. 1A-1C, the implantable device 100 may includea plurality of cutting fins 120 on the elongate main body 110. Thecutting fins 120 may be oriented in a helical fashion along the mainbody 110, such that the fins 120, if extended so as to be continuous(i.e., each fin is connected to an adjacent fin) would form a helicalthread that runs along the length of the main body 110. It iscontemplated that the cutting fins 120 would help to anchor the device100 into the facet being treated, and prevent the device 100 frombacking out. More importantly, the cutting fins 120 would help toinitiate a physiological response akin to fracture healing at the siteby cutting into, scraping, and generally causing bone bleeding as thedevice 120 is seated into the facet. In this regard, the cutting fins120 would also help serve as a mechanical scaffold for new bone growtharound and in between the fins 120. Although the fins 120 are shown aswedge-shaped, it is understood that the fins 120 may comprise othershapes, such as V, W or wave-shaped. For instance, the fins 120 maycomprise bands of ridges or teeth.

FIGS. 2A and 2B illustrate another exemplary embodiment of animplantable device 200 of the present disclosure. Like implantabledevice 100, this device 200 may comprise an elongate main body 210 thatterminates at a first, leading end 212 and at a second, trailing end 214at the opposite end. The first, leading end 212 may include a taperednose 216. The tapered nose 216 may have a very sharp terminal edge thatfacilitates cutting into bone tissue during insertion. This edge couldbe smooth, or roughened or jagged.

Similar to the previous implantable device 100, the main body 210 may becannulated for use with a guidewire. Implantable device 200 may beinserted in the same manner as described for implantable device 100, andfurther as will be described below. Accordingly, the second, trailingend 214 of the implantable device 200 may include a tool-engagingopening 222, as shown in FIG. 2B. Implantable device 200 may furtherinclude a plurality of openings 230 along the length of the main body210. These openings 230 may allow for bony ingrowth through the device200.

FIGS. 3A-3C illustrate yet another exemplary embodiment of animplantable device 300 of the present disclosure. Implantable device 300combines some of the features present in each of the implantable devices100, 200 previously described. Implantable device 300 may comprise anelongate main body 310 having a first, leading end 312 and a second,trailing end 314 at an opposite end. The first, leading end 312 may havea tapered nose 316. The tapered nose 316 may be configured to have avery sharp terminal edge to facilitate cutting into bone tissue duringinsertion. The terminal edge could be smooth, as shown, or it could alsoencompass a jagged, roughened edge if so desired.

The main body 310 may be cannulated and include central channel 318 foruse with a guidewire. As will be described in more detail below, thesecond, trailing end 314 of the implantable device 300 may be configuredwith a tool-engaging opening 322, as shown in FIG. 3C. This opening 322allows the device 300 to be attached to an insertion tool for drivingthe device 300 into the bone to be treated.

Along the length of the main body 310 are cutting fins 330 that may beoriented in a helical-spiral fashion. The fins 330 may be wedge-shaped,as shown. Alternatively, the cutting fins 330 may comprise other shapes,such as S, V, W or wave-shapes. For instance, the cutting fins 330 maycomprise bands of ridges or teeth.

Also on the main body 310 are grating holes 340. These grating holes 340include a raised cover 342 having a sharp, cutting edge as shown inFIGS. 3A and 3B that resides over a portion of the grating hole 340. Inuse, as the implantable device 300 is inserted, the cutting fins 330 andgrating holes 340 help to cut into and scrape the pre-drilled hole inthe facet bone where the device 300 is being placed. Excess bone tissuemay be directed inside the main body 310 through the grating holes 340,while the cutting fins 330 help to anchor the device 300 in the bone andprevent the device 300 from backing out. In some cases, the gratingholes 340 may allow for some bony ingrowth into the device 300.

FIG. 4 illustrates still yet another exemplary embodiment of animplantable device 400 of the present disclosure. Implantable device 400may comprise an elongate main body 410 having a first, leading end 412and a second, trailing end 414 at an opposite end. The first, leadingend 412 may have a tapered, sharp tip 416 for piercing through bone andsurrounding tissue. Additional structural features could be provided onthe tip 416 to facilitate its cutting into bone tissue during insertion,such as for example, barbs, threads, or raised cutaway portions tocreate a jagged cutting edge. The tip 416 may extend into a series ofhelically wound coils 450 all the way to the second, trailing end 414.These coils 450 may be packed, or wound closely together, or they may beconfigured with a gap in between. The coiled body 410 serves as a fusioncage, and can allow bone growth to occur throughout, thereby furtherenhancing anchorage of the implantable device 400 to the patient'sanatomy.

FIG. 5 illustrates even still another exemplary embodiment of animplantable device 500 of the present disclosure. Implantable device 500may comprise an elongate main body 510 having a first, leading end 512and a second, trailing end 514 at an opposite end. Like in previousembodiments, the first, leading end 512 may include a tapered nose 516to ease insertion into the bone. The tapered nose 516 may have a verysharp terminal edge, or include surface features such as barbs, threads,or cutaway portions to create a jagged cutting edge to facilitatecutting into bone tissue during insertion. The second, trailing end 514may further include a tool-engaging opening 522 to allow the device 500to be attached to an insertion tool for driving the device 500 into thebone to be treated.

The main body 510 may comprise a series of helically wound coils 550extending from the tapered nose 516 to the second, trailing end 514.Similar to implantable device 400, these coils 550 may be packed, orwound closely together, or they may be configured with a gap in between.Similarly, the coiled body 510 may serve as a cage, and allow bonegrowth to occur throughout, thereby further enhancing anchorage of theimplantable device 500 to the patient's anatomy.

While implantable devices 100, 200, 300 can have a general appearanceof, and function similarly to, a bone screw, implantable devices 400,500 can have a general appearance of, and function more similarly to,fusion cages. Thus, it can be appreciated that the implantable devicesof the present disclosure may share numerous structural designs to otherfusion-promoting devices currently known to achieve the desired result.

The implantable devices 100, 200, 300, 400, 500 of the presentdisclosure may be formed of any suitable medical grade metal. Suitablemetals may include, but are not limited to, stainless steel, titanium,titanium alloys, and cobalt chrome, as examples. Porous metals may alsobe appropriate. Of course, the devices 100, 200, 300 may also be formedfrom a variety of other suitable biocompatible materials, either aloneor in combination with one another. The devices may also be ABSinjection molded plastic, polyetheretherketone (PEEK), polyethylene(PE), or ultra high molecular weight polyethylene (UHMWPE). If desired,the devices may be bioabsorbable or bioresorbable. In other embodiments,the implant may be formed partially or wholly from a radiolucentmaterial. For example, the implant may be formed from a material blendedwith a radiopaque material, such as barium sulfate. In addition,radiopaque markers may be employed with the implant for imagingpossibilities. Where a semi-rigid implantable device is desirable, it ispossible to combine rigid materials with other semi-flexible materialssuch as silicone or another rubber-like material to form a semi-rigid,semi-flexible device that is still capable of withstanding normalcompression loads.

Other examples of suitable synthetic polymers include, but are notlimited to, polyvinyl alcohol (PVA) and alkylated or acylatedderivatives thereof, polyurethane (PU), polypropylene (PP), nylon,polycaprolactone (PCL), and copolymers and combinations thereof.Examples of suitable synthetic non-biodegradable polymers, include, butare not limited to, various polyacrylates, ethylene-vinyl acetates (andother acyl-substituted cellulose acetates), polystyrenes, polyvinyloxides, polyvinyl fluorides, poly(vinyl imidazoles), chlorosulphonatedpolyolefins, polyethylene oxides, polytetrafluoroethylenes and nylons.Another polymeric material, which is particularly suitable for use inproduction of mouldable compositions, is a hydrolysed polymer orcopolymer of a vinyl ester, particularly a hydrolysed polymer orcopolymer of vinyl acetate.

In addition, the implantable devices 100, 200, 300, 400, 500 of thepresent disclosure can be enhanced with biologically active features topromote fusion and new bone growth. In one embodiment, the biologicallyactive feature may be native to the material forming the device. Forinstance, the device may be formed entirely of or coated with bioactiveglass (“BAG”). In another embodiment, the surface of the implantabledevices 100, 200, 300, 400, 500 may include biologically active agents.The biologically active agent may be contained in a coating on thedevice 100, 200, 300, 400, 500. These agents may includeosteoconductive, osteoinductive, or osteogenic factors to furtherfacilitate bonding between the devices 100, 200, 300, 400, 500 and thesurrounding bone tissue. The biologically active agent may be, forexample, bone morphogenic protein (BMP) for modulating cartilage or bonegrowth, platelet rich plasma (PRP), bone marrow aspirate (BMA),demineralized bone matrix (DBM), stem cells, or allograft material, forexample. Furthermore, a bioactive surface may be created on the devicesby treating the implantable devices with, for example, acid etching,grit blasting, plasma spraying, bioactive glass coating, photo-chemicaletching, or other suitable surface treatments for creating a roughenedsurface. Additionally, the implantable devices 100, 200, 300, 400, 500may include therapeutic agents such as antibiotics, steroids,anti-thrombotic agents, anti-inflammatory drugs, and/or analgesicagents.

Alternatively, or in addition, these agents may be embedded within thedevices. For example, the device may be porous, and the biologicallyactive agent may be contained in the pores of the device. In stillanother embodiment, the biologically active feature may be a separatecomponent usable in combination with the device. For instance, a bonegraft insert may be employed inside the devices 100, 200, 300, 400, 500of the present disclosure.

The implantable devices 100, 200, 300, 400, 500 of the presentdisclosure may be used to treat degenerative facet disease or facetarthritis. FIGS. 6A-6G illustrate an exemplary method of usingimplantable devices 100, 200 to treat a diseased facet joint that needsimmobilizing due to degradation. The facet joint 8 may be part of avertebra 6 in the cervical portion 4 of a patient's spine 2. As shown inFIG. 6A, a guidewire 10 may be inserted into the targeted facet 8 to betreated. Once the guidewire 10 has been properly placed, a dilator tubeor cannula 20 may be placed over the guidewire 10, as shown in FIG. 6B.Then, a drill bit 30 may be placed through the cannula 20, as shown in acutaway view of FIG. 6C. Next, a pilot hole is drilled into the facetjoint 8 to receive the implantable device 100, 200. The pilot hole mayhave a slightly smaller diameter than the outer diameter of theimplantable device 100. For example, the pilot hole could beapproximately 2.7 mm in diameter for a 3.0 mm device.

Due to the very tight space surrounding the cervical spine 4, therelative curvatures of the patient's natural anatomy are even morepronounced in this cervical region 4 of the spine 2. Thus, it isdesirable to provide a drill bit 30 that may be able to bend or curvealong with the contours of the facet or facet joint 8. FIGS. 6D and 6Eillustrate one exemplary embodiment of a multi-linked articulating drillbit 32 comprising one or more drill bits 34 that can be independentlycontrolled so that the clinician or user may be able to achieve a moreangular or curved approach. The entire drilling process may be done overthe guidewire 10. Proper drilling techniques are critical to the successof the method, since the drilling acts as burring or debridement,stimulating the patient's natural healing response. In addition, properdrilling into the narrow structure of the weakened facet 8 will preventover-drilling or over-angulation that could cause further damage to theweakened structure and cause breakage of the existing bone.

Once the pilot hole and insertion path has been achieved, theimplantable device may be inserted into the facet joint 8. As shown inFIG. 6F in which implantable device 200 is being delivered, the device200 may be delivered along the same path as the drill bit 32 previouslymade. It would be preferable for the cannula 20 to allow some bending aswell, as illustrated in FIG. 6F, to facilitate ease of insertion. Havingthe ability to bend slightly and conform to the contours of thepatient's anatomy will reduce the overall force needed to be exerted,and prevent breakage or damage due to excessive force. Thus, as shown, aflexible cannula 20 could be preferably used in this method.

As FIG. 6G illustrates, implantable device 100 may be attached at itstool-engaging end to a driver such as an insertion tool 50 as iscommonly used in the art. The implantable device 100 may then beinserted through cannula 20 into the pilot hole with slight twistingaction to seat the device 100 inside the hole. The pilot hole itself maybe in the range of about 6-9 mm in length to accommodate an implantabledevice of about the same length. In some cases, the implantable device100 may be press fitted into place.

As the implantable device 100 is inserted, it is contemplated that thecutting fins 120 would help to initiate a physiological response akin tofracture healing at the site by roughening up the bone tissue of thepilot hole. The cutting and scraping of bone tissue, along with bonebleeding, triggers a healing response or fusion of the joint. Theimplantable device 100 further serves as a mechanical scaffold for newbone growth around and in between the fins 120, which also help avoidback out. In the case of implantable device 300, the grating holes 340would allow for some of the scraped bone tissue to be scooped into themain body 310, thereby also allowing bony ingrowth through the device300.

FIG. 6H illustrates the implantable device 100 in situ, properlysituated within the facet joint being treated. Once the implantabledevice 100 is in place, the same steps may be repeated on the other sideof the spine 2. It is contemplated that the entire process can beperformed using fluoroscopy for visualization.

While the invention is described in the context of osteoarthritis of thespine, and particularly the cervical spine, it is not limited to suchcondition. Other conditions that can be treated in accordance with theinvention include but are not limited to osteoarthritis of joints otherthan the spine. For example, the implantable devices may be used totreat other joints, such as the shoulder, hip, and knee. In particular,the implantable devices of the present disclosure may have particularapplicability in small bone joints such as the ankle, foot, hand, andfingers. Moreover, in some embodiments, the implantable devices may becoupled to other forms of joint pain treatment. For instance,implantation of the facet fusion devices may be employed in conjunctionwith other procedures. In such cases, the implantable device itselfbecomes a component in a multi-step treatment process to address theoverall pain management and treatment of the joint.

In another embodiment, the implantable devices 100, 200, 300, 400, 500may be inserted along a perpendicular plane into the facet joint. Asdescribed above and as shown in FIGS. 6A-6H, the implantable devices areinserted along the facet joint line, or along the joint plane. Forinstance, one method of implanting the device would approach from theposterior and medial, and angle anterolateral along the plane of thejoint.

However, it is contemplated that the implantable devices of the presentdisclosure could also be inserted so as to cross the facet joint line,as shown in FIG. 6I. In such an arrangement, the implantable devicewould reside in a plane perpendicular to the joint plane. In thisembodiment the approach would still be from the posterior, but wouldcome from a superior to inferior angle crossing the joint, rather thaninferior to superior along the joint plane. That is, the implantabledevice could be inserted from the posterior and medial, and angleinferior and lateral across the joint.

Other embodiments of the invention will be apparent to those skilled inthe art from consideration of the specification and practice of thedisclosure provided herein. It is intended that the specification andexamples be considered as exemplary only, with a true scope and spiritof the disclosure being indicated by the following claims.

What is claimed is:
 1. An implantable device for cervical facet fusion,comprising: an elongate main body extending between a first, leading endand a second, trailing end, the first, leading end terminating into atapered nose, the elongate main body being configured for insertion intoa cervical facet, and a plurality of cutting fins extending from theelongate main body, each of the cutting fins having a tapered bodylengthwise and a sharp, cutting edge, the cutting fins collectivelyforming a discontinuous helical thread spiraling down the length of theelongate main body.
 2. The device of claim 1, wherein the tapered noseincludes a sharp cutting edge.
 3. The device of claim 1, furtherincluding a tool-engaging opening at the second, trailing end.
 4. Thedevice of claim 1, wherein the elongate main body is cannulated.
 5. Thedevice of claim 1, further being biologically active.
 6. The device ofclaim 5, wherein the device includes a biologically active coating. 7.The device of claim 5, wherein the device is formed of a biologicallyactive material.
 8. The device of claim 5, wherein the device includes abiologically active material.
 9. A method of treating degeneration of afacet joint, comprising: providing an implantable device having anelongate main body extending between a first, leading end and a second,trailing end, the first, leading end terminating into a tapered nose,the elongate main body being configured for insertion into a cervicalfacet, and a plurality of cutting fins extending from the elongate mainbody, each of the cutting fins having a tapered body lengthwise and asharp, cutting edge, the cutting fins collectively forming adiscontinuous helical thread spiraling down the length of the elongatemain body; drilling a pilot hole into a targeted site of the facet jointto be treated; inserting the implantable device into the pilot hole; anddelivering the implantable device into the targeted site.
 10. The methodof claim 9, wherein the facet joint is a cervical facet joint.
 11. Themethod of claim 9, wherein the step of drilling causes debridement. 12.The method of claim 9, wherein the pilot hole has a diameter smallerthan an outer diameter of the implantable device.
 13. The method ofclaim 9, wherein the pilot hole is non-linear.
 14. The method of claim13, further including the step of using an articular drill bit to drillthe pilot hole.
 15. The method of claim 9, further including the step ofinserting a guidewire to the targeted site of the facet joint to betreated.
 16. The method of claim 9, further including the step ofidentifying a second targeted site of a facet joint to be treated, thesecond targeted site located on an opposite side of the spine.
 17. Themethod of claim 16, further including repeating the steps of drilling,inserting and delivering to the second, targeted site.
 18. The method ofclaim 9, wherein the implantable device is placed along a plane of thefacet joint.
 19. The method of claim 9, wherein the implantable deviceis placed across the facet joint.